The present invention relates to power machinery. More particularly, the present invention relates to a control system for a work machine. Although compact tractors, skid steer loaders and other types of wheeled work machines have enjoyed great success and are used throughout the world in a number of different applications, these machines are not well suited for all work environments. For example, compact tractors, while useful in some applications, frequently have a number of characteristics, which limit their usefulness in other applications. Typically, compact tractors have poor visibility to the front (i.e., toward the bucket). Compact tractors also typically have limited hydraulic systems for operation of attachments, and the attachments are frequently behind the operator, forcing the operator to turn around to see them. Further, for the operator of the compact tractor, entry/egress is often awkward or difficult and usually the tractor only provides seating for a single person. Also, compact tractors lack a cargo area, which severely limits their usefulness in many applications. Other common limitations of compact tractors include a relative lack of stability and the rough ride provided by many compact tractor designs.
Utility carts are another type of wheeled work machine, which have a number of characteristics that limit their usefulness in some applications. For example, utility carts do not have a loader option, and typically have limited or no attachment capability. Also, utility carts generally have limited, if any, onboard hydraulic systems for the operation of hydraulic attachments. Other typical characteristics of utility carts, which limit the applications in which they can be used, include a relatively large turning diameter and a limited ability to carry cargo. Utility carts are frequently low on power needed to pull equipment or carry cargo.
In many applications, a small turning diameter would be a beneficial feature of a wheeled work machine. However, many wheeled work machines, if not most, do not have small turning diameters. Thus, to change direction of travel, these machines need to stop, change direction, reorient the machine, and proceed in the intended direction. Typically, machines with front steerable wheels (for example, tractors and most utility vehicles) have to maintain a short wheelbase in order to maintain a small turning diameter, as wheelbase and turning diameter are inversely proportional. However, a short wheelbase has a negative effect by decreasing lift capacity, operator area, cargo area, etc.
Most compact tractors maintain a relatively small turning diameter by turning the front wheels extremely sharply and generally having a shorter wheelbase. Turning the wheels excessively sharp can be damaging to sensitive grounds such as lawns and turf areas. Further, even with a short wheelbase (and the disadvantages which result), the relatively small turning diameter of compact tractors may not be small enough for some applications. Most utility carts have a large turning diameter, which is unacceptable for many applications, due to the fact that they cannot turn the wheels as sharply as a typical tractor and that they require a longer wheelbase to place the operator seating, engine, cargo area, etc. A wheeled work machine which provides a small turning diameter without the disadvantages associated with the short wheelbase of tractors, would be a significant improvement in wheeled work machine applications.
Generally, wheeled work machines such as compact tractors, utility carts, and other types have numerous limitations, which prevent them from being suited for some applications. Some of these limitations are discussed above with reference to compact tractors and utility vehicles, but they may apply to other types of work machines as well. In addition to turning diameter characteristics, a common limitation in many wheeled work machines is a general inability to carry more than one person to a work site. Other limitations include an inability to carry cargo, poor visibility, lack of attachments such as a bucket or loader, low power, and instability, to name a few.
Further, many such machines have no mechanism for sensing operator presence or operator position.
Skid steer loaders have proven to be highly useful in many applications. Skid steer loaders have features, which are often highly beneficial for certain work environments. For example, skid steer loaders can support a wide variety of work tools and attachments. Skid steer loaders can also be turned very sharply. Numerous other features of skid steer loaders provide these machines with highly advantageous capabilities. Although skid steer loaders have enjoyed great success and are used throughout the world in a number of different applications, the skid steer loader is not well suited for all work environments.
There is thus a continuing need for an improved wheeled work machine. A machine that addresses one, several or all of the deficiencies discussed above would be particularly advantageous.